"Sooner or later, all heat from the tokamak, the plant and the ITER buildings is released into the atmosphere," says Alfonso Marquez, Section Leader for plant installation. "Cold water is pumped out to different clients and buildings, where it picks up the heat. The hot water is then circulated back to our plant, where it is cooled down through a series of steps."
ITER's high-performance heat rejection system covers a 6,000 m² area on the northern corner of the platform. Hot and cold cooling water basins, powerful pumps (10 horizontal, 13 vertical), 17 heat exchangers, and an induced-draft cooling tower with ten individual cells are part of the infrastructure that will remove the heat load from the ITER vacuum vessel, its plasma-facing components, heating and power systems, and buildings.
The cooling towers are designed to release a maximum of 500 MW. During a peak, rather than try to process all the heat contained in the hot water at once (1145 MW), some of it is stored in a 9-metre-deep basin, which serves as a heat sink. From there, it is pumped progressively into the cooling tower.
The cooling plant has to handle the cyclical nature of ITER operation, where ''burn'' phases (with peak heat loads reaching 1145 MW) are followed by ''dwell'' phases, where loads drop off to 160 MW. The design of the plant optimizes the management of this intermittence, in order to reduce its footprint and cost.